// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IPC_MESSAGE_FILTER_H_
#define IPC_MESSAGE_FILTER_H_

#include <stdint.h>

#include <vector>

#include "base/memory/ref_counted.h"
#include "ipc/ipc_export.h"

namespace IPC {

class Sender;
class Message;

// A class that receives messages on the thread where the IPC channel is
// running.  It can choose to prevent the default action for an IPC message.
class IPC_EXPORT MessageFilter
    : public base::RefCountedThreadSafe<MessageFilter> {
public:
    MessageFilter();

    // Called on the background thread to provide the filter with access to the
    // channel.  Called when the IPC channel is initialized or when AddFilter
    // is called if the channel is already initialized.
    virtual void OnFilterAdded(Sender* sender);

    // Called on the background thread when the filter has been removed from
    // the ChannelProxy and when the Channel is closing.  After a filter is
    // removed, it will not be called again.
    virtual void OnFilterRemoved();

    // Called to inform the filter that the IPC channel is connected and we
    // have received the internal Hello message from the peer.
    virtual void OnChannelConnected(int32_t peer_pid);

    // Called when there is an error on the channel, typically that the channel
    // has been closed.
    virtual void OnChannelError();

    // Called to inform the filter that the IPC channel will be destroyed.
    // OnFilterRemoved is called immediately after this.
    virtual void OnChannelClosing();

    // Return true to indicate that the message was handled, or false to let
    // the message be handled in the default way.
    virtual bool OnMessageReceived(const Message& message);

    // Called to query the Message classes supported by the filter.  Return
    // false to indicate that all message types should reach the filter, or true
    // if the resulting contents of |supported_message_classes| may be used to
    // selectively offer messages of a particular class to the filter.
    virtual bool GetSupportedMessageClasses(
        std::vector<uint32_t>* supported_message_classes) const;

protected:
    virtual ~MessageFilter();

private:
    friend class base::RefCountedThreadSafe<MessageFilter>;
};

} // namespace IPC

#endif // IPC_MESSAGE_FILTER_H_
